Chair base



Oct. 6, 1964 J. P. GIACOMINI CHAIR BASE 2 Sheets-Sheet 1 Filed May 15,1963 m m w.

ATTORNEY Oct. 6, 1964 J. P. GIACOMINI CHAIR BASE 2 Sheets-Sheet 2 FiledMay 15 1963 INVENTOR. J fAN P. 61,4 COM/NI United States Patent3,151,830 CHAIR BASE Jean P. Giacomini, York, Pa., assignor to ThonetIndustries, Inc., New York, N.Y., a corporation of Delaware Filed May15, 1963, Ser. No. 281,385 Claims. (Cl. 248-1883) This inventionpertains to improvements in a chair base and, more particularly, a chairbase particularly designed for a swivel chair.

Chair bases of the type referred to conventionally comprise a centralhollow post or column from the lower portion of which a plurality ofradially extending legs or prongs project, casters usually being mountedin the outer ends thereof. At least three legs or prongs of such typeare provided and, in most chair bases, a set of four legs are employed,opposite pairs thereof being in alignment with each other and said pairscrossing each other transversely, whereby all of the legs extendsubstantially at 90 to each other.

Chair bases of this type have been made for many years from wood anddovetailed grooves have been employed extending axially of the centralcolumn to receive complementary configurations on the inner ends of thelegs which are to project radially from the column. Lastly, a metalmember having radially extending ears usually is mounted across thelower surfaces of the inner end portions of the legs and heavy screwsare employed to secure said ears to the legs, especially to brace thelegs against upward movement at the outer ends thereof relative to thecolumn.

In recent years, metal has been employed for purposes of forming thistype of chair base, the radially extending legs and central post orcolumn all being formed from suitable metal, such as aluminum.Satisfactory but relatively expensive bases can be formed from suchmeans, especially where all of the legs are formed from a unitarycasting or stamping, to the center of which the vertical post or columnis affixed. In an eifort to reduce the cost of such type of metallicchair base and still provide one having satisfactory strength, however,substantial problems have been presented and, until the advent of thepresent invention, no readily satisfactory solution to these problemshas been presented.

It is the principal object of the present invention to provide a chairbase formed from suitable metal, such as aluminum, having legs which areseparable at the inner ends thereof from the central column and thecomponents of the base readily can be formed, at least in the main, fromstandard stock tubes, plates, and the like, by the employment ofconventional machining operations as distinguished from any requirementto use castings, Weldments, or other similar expensive features.

It is another object of the invention to provide in the aforementionedchair base arrangement readily disconnectable means by which one or moreof the legs or prongs quickly can be removed from the base and replacedby a new one, should occasion arise for doing so, and the base then maybe restored to fully useful condition through the employment of simplemeans and tools such as, principally, a screw driver and screws.

At still further object of the invention is to provide a chair baseembodying the above-described principles of the invention and alsohaving a highly appealing aesthetic appearance and finish coupled withmaximum required strength to resist deformity and loosening of any ofthe connected members even during rugged use of the chair base.

Still another object of the invention is to provide means which jointlyserve to improve the aesthetic appearance of the central column andinner end of the legs and, in

3,151,830 Patented Oct. 6, 1964 addition, cooperate with the connectingmeans to effect a firm attachment of the inner ends of all of the legswith the central column.

Details of the foregoing objects and of the invention, as well as otherobjects thereof, are set forth in the following specification andillustrated in the accompanying drawings comprising a part thereof.

In the drawings:

FIG. 1 is a perspective view of an exemplary swivel chair having a baseembodying the principles of the present invention and shown supportingan exemplary seat and back combination, the latter being illustrated inphantom.

FIG. 2 is a fragmentary side elevation of the central column and innerends of the legs which are connected thereto, parts of the centralcolumn structure being broken away to illustrate details.

FIG. 3 is a fragmenary top plan view of the chair base shown in FIG. 2as seen on the line 22 of FIG. 2.

FIG. 4 is a bottom plan view of the chair base shown in FIGS. 1 and 2,the scale used in FIG. 4 being greater than that employed in FIG. 2,which, in turn, is greater than that utilized in FIG. 1.

FIG. 5 is a fragmentary vertical sectional View similar to that shown inFIG. 2 but illustrated on a larger scale than in FIG. 2 and illustratingmore details of the connecting means than is shown in FIG. 2.

FIG. 6 its a perspective view of the inner, central portion of thecompound column illustrated in FIGS. 2 and 5 but shown on a smallerscale than in said figures.

FIG. 7 is a perspective view of a finishing and locking sleeve whichsurrounds the inner central portion of the column shown in FIG. 6.

FIG. 8 is an upper perspective view of the locking member which isconnected detachably to the lower end of the inner central column membershown in FIG. 6.

FIG. 9 is a fragmentary perspective view of the inner ends of one of thelegs to illustrate clearly the details of the dovetailed connectingconfiguration ananged thereon.

FIG. 10 is a fragmentary Vertical sectional View of the outer end of oneof the legs illustrated in FIG. 1.

Referring to FIG. 1, the chair base 10, which embodies the principles ofthe present invention, is shown in full lines supporting an exemplarycombination chair seat and back 12 which is illustrated in phantom. Itis to be understood that the chair base 10 may be employed with anydesired type of chair seat and/ or back, however, within thecontemplation of the present invention. Preferably, the chair base 10 isintended to be used with a central shaft means, usually threaded, whichis connected to and depends from the bottom of the seat of the chair inaccordance with conventional practice. Usually, the connecting meansbetween the central column or post of the chair base and the shaft whichdepends from the chair seat is such as to permit vertical adjustmentbetween the base and chair seat, this also being in accordance withconventional practice.

As indicated above, the chair base 10 preferably is fabricated fromelements capable of being produced from substantially standard stockmaterial such as tubes and sheet stock of a metallic nature. Theconnection of the finished elements to each other quickly and firmly isachieved by relatively simple connecting means. The actual fabricationof the various components which are articulated to comprise the finishedbase is accomplished on conventional machine tools such as lathes,milling machines, and the like.

Any suitable structural metal from which metallic furnitureconventionally is made may be utilized in the manufacturing of the base.However, aluminum especially is suitable as a material for forming atleast most of the components, primarily because it provides its ownnatural finish which is highly acceptable aesthetically in furniture ofthis type. Further, suitable colors and finishes may be applied toaluminum, other than its natural finish, such as by anodizing the same.It is not intended to restrict the base to being formed from aluminum inaccordance with the invention, however, since other metals such assteel, stainless steel, brass, and the like, may be employed.

The central column or post 14 is composite, as is best seen from FIGS.and 6. The inner, central member 16 may be formed, for example, eitherfrom round bar stock, and centrally drilled or bored, or it may beformed from heavy walled tubing of suitable size. The upper end portionof the member 16 is reduced in diameter to form an upper threaded end18, for purposes to be described. The lower end of member 16 is providedwith transversely crossed slots 20, disposed at 90 to each other, saidslots readily being susceptible of being formed in the lower end ofmember 16 by a milling cutter. The upper ends 22 preferably extendupward and inward so as to be disposed at an angle to the axis of member16, other than 90, thereby comprising one side of a mortise of adovetailed connection, details of which are explained hereinafter. Theterminal end 24 of member 16 also preferably is beveled after beingslightly reduced in diameter, the exact preferred shape thereof beingbest illustrated in FIG. 5,

this arrangement also being for purposes to be described hereinafter.

The radially extending, cantilever type legs 26 preferably are identicaland, in accordance with the preferred construction of the invention, areformed from flat sheet metallic stock, such as aluminum, of the order ofapproximately inch or /2 inch thickness. Especially for aestheticpurposes, and as seen in FIG. 1, the outer ends of the legs 26 have ashorter vertical dimension than the inner ends thereof, and the bottomsurfaces of the legs preferably being within a common horizontal plane,whereby the upper surfaces extending outward and downward.

Aflixed to the outer ends of each leg is a socket-forming tube 28 whichis secured thereto by a pair of screws '30. Said screws are afiixed byprojecting the same through a pair of vertically spaced holes 32 formedtransversely in an outer wall of the tube 28 and then extending the samethrough suitable counter-sunk holes 34 in the opposite wall of tube 28,as clearly shown in FIG. 10. The holes 32 then are hidden by a suitablecap 36 which preferably fits, frictionally, over the external surface oftube 28 and likewise covers the top thereof as shown in FIG. 10. Thetube 28 and its assembled cap 36 thereby comprise an appropriate sockethaving a central bore 38 to receive the shank of a caster 40, which isshown in exemplary manner in FIG. 1, or any type of glide.

The opposite or inner ends of the legs 26 are each pro- .vided in theupper surface thereof with an undercut notch 42 which defines one sideof a dovetail tenon 44, the lower surface of said dovetail tenon havinga notch extending upwardly thereinto from the lower edge and defining adownwardly extending hook-like projection 46, which is best shown inFIG. 9. However, the projection 46 functions similarly to the undercutnotch 42 with respect to defining in general, the dovetail tenon 44.

The legs 26 and tenons 44 preferably are of the same thickness in atransverse direction with respect to the broad surfaces of the legs andsaid thickness is closely complementary to the width of the slots 20within which the tenons 44 are disposed snugly. Said tenons are insertedwithin said slots vertically upward, as viewed in FIGS. 2 and 5, untilthe undercut surfaces of the notches 42 engage the upper ends 22 of theslots 20 firmly. The vertical walls 48 of notches 42 also preferablyabut, in firm manner, the exterior surfaces of the inner central member16 as can be seen to advantage from FIG. 5. This arrangement preventsany inward radial movement 4 I of the upper ends of the legs withrespect to the central column 14.

Affixed to the lower end of the inner central member 16 is a lockingcollar 59 which, preferably, is circular, as shown in FIG. 8, and has acentral hole 52 therein. The lower surface of collar 56, when mountedoperatively in position against the lower end of inner central member16, preferably is planar and is disposed within the general plane inwhich the lower surfaces of the legs 26 are disposed.

The upper surface of said collar is centrally undercut to provide anupwardly extending locking flange 54, the inner wall of which iscomplementary to the terminal end 24 of the inner central member 16, asis clearly shown in FIG. 5. Referring further to FIG. 5, is will be seenthat the inner surface of the annular flange 54 of locking collar 50 notonly is complementary to the terminal end 24 of inner central member 16but is also complementary to the hook-like projection 46 on the lowerportion of the inner end of each leg 26. Therefore, the locking flange54 and hook-like projections 46 interlock with each other in such amanner as to have a very substantial ability to resist outward lateralmovement of the lower portions of the legs 26 away from the axis of thecentral column 14. Further, this is accomplished very effectivelythrough the simple expedient of a plurality of detachable screws 56which extend through complementary holes 58 in locking collar 50 andinto additional complementary tapped holes extending upwardly into thelower end of inner central member 16 of column 14. The heads of screws56 may be either of the roundhead type, as illustrated in FIG. 5, orbeveled headed if desired.

From the foregoing, it will be seen that the substantially dovetailedtenons 44 on the inner ends of each of the legs 26 effectively areclamped between the complementary surfaces of the upper ends 22 of slots20 and the inner surfaces of annular flange 54 on locking collar 50. Thedimensions of the coengaging surfaces and the elements upon which theyare formed are such that,

when the screws 56 firmly secure the locking collar 50 to the lower endof inner central member 16 of column 14, the tenons 44- on the innerends of the legs 26 will be firmly and securely connected to the lowerend of column 14 so as to prevent any significant relative movement ofany kind between said legs and column.

Notwithstanding the above-described arrangement, still further securingmeans are provided by sleeve 60, the inner surface of which is closelycomplementary to the exterior surface of inner central member 16. Veryaccurately formed within the lower end of sleeve 60 are a plurality ofcircumferentially evenly spaced slots 62 which are parallel to the axisof the sleeve 68 and the inner or upper ends 64 of slot 62 preferablyare disposed accurately within a common plane to which the axis ofsleeve 60 is quite precisely vertical.

The length of slots 62 also preferably is substantially equal to thegreatest vertical dimension of the inner ends of the legs 26, as bestshown in FIG. 5, whereby when the sleeve 60 is disposed around the innercentral member 16 and the slots 62 therein are disposed in coincidencewith the slots 20 of member 16, and assuming further that the tenons 44on the legs have been secured within the slots 20 of member 16 by thelocking collar 50 being accurately secured in locking position, thesleeve 60 not only constitutes an aesthetically attractive finishingsurface for the composite central column 14 but it also performs anadditional function. Such additional function comprises the employmentof a locking ring 66 which is interiorly threaded to engage the threadsof the upper end 18 of inner central member 16 and the upper end oflocking ring 66 either is formed with a suitable crosssectionalgeometric shape, such as a hexagon, to facilitate the use of a wrenchthereon, or a suitable notch may be formed at a desired location thereinfor purposes of receiving the lug of a spanner wrench in order that thelocking ring 66 may be tightened downwardly.

When the locking ring 66 is rotated in tightening direction against theupper end of sleeve 60, it will force the upper ends 64 of slot 62firmly into engagement with the upper surfaces of the inner ends of legs26 and thereby additionally insure firm and positive engagement, of aninterlocking nature, between the locking flange 54 and collar 50 and thehook-like projections 46 on tenons 44. Firm connection between theselatter interlocking members is of greater importance than firminterengagement between the upper ends 22 of slots 20 and the angularsurfaces of undercut notches 42 which abut the same because it is theinterlocking movement of flange 54 and projections 46 which prevents anyupward movement of the outer ends of the legs 26 with respect to thecentral column 14.

Notwithstanding the very firm connection of the legs 26 to the centralcolumn 14 which is afforded by the interlocking elements describedabove, it nevertheless will be seen that, simply by removing the screws56 and then removing the locking collar 50 from the lower end of theinner central member 16, any one of the legs 26 may easily and readilybe removed by simple tapping upon of the same, downwardly with respectto central column 14, and such removed leg then either may be replacedor a new one substituted therefor, as desired, followed by firmconnection of the inner end thereof to the central column 16 in themanner described above, by means of locking collar 50.

The inner central member 16 preferably is provided with a central bore68 which receives an exemplary threaded central shaft 70, thefragmentary lower end of which is shown in FIG. 5. Such shaft 70 isconventionally employed on a swivel chair arrangement to which the basecomprising the present invention particularly is well adapted for use.To support the chair seat 12 at a desired elevation with respect to thebase 10, appropriate conventional means are utilized such as bearingcollar 72 which is threadably secured to the threaded upper end 18 ofinner central member 16, as shown in FIG. 5, said collar beingpreferably locked against rotation by means such as a set screw.

Threadably adjustable on the central shaft 70 is a cup-like member 74which has a skirt on the lower end thereof extending to the vicinity oflocking ring 66, said member 74 also having an inner, annular bearingsurface abutting the upper end of bearing collar 72, while a screw 76 orother similar locking means extends through the lower wall of member 75and projects beneath the lower surface of bearing collar 72 in orderthat when the chair seat 12 is picked up from the floor, the base willnot be separated therefrom.

From the foregoing, it thus will be seen that the present inventionprovides a readily fabricated and easily assembled chair base capable ofbeing manufactured from standard stock material by conventional machinemethods, yet affording easy detachability of any of the legs from thecentral column of the base, the overall construction and arrangementalso being aesthetically pleasing and attractive. The base is alsocapable of rugged use without loosening of the legs with respect to thecentral column of the base over long periods of time.

While the invention has been described and illustrated in its severalpreferred embodiments, it should be understood that the invention is notto be limited to the precise details herein illustrated and describedsince the same may be carried out in other ways falling Within the scopeof the invention as claimed.

I claim:

1. A chair base comprising a central substantially vertical columnhaving a plurality of radial open-ended recesses extending verticallyupward from the lower end thereof, and a plurality of cantilevermetallic legs extending radially outward spider-like from the lower endof said column in circumferentially spaced relationship to each otherand the inner ends of said legs being closely complementary to andreceived within said recesses, in combination with means detachablyconnecting said inner ends of each leg within said recesses of saidcolumn comprising locking means detachably connected to the lower end ofsaid column, the inner ends of said legs having notches emendingupwardly from the lower surfaces thereof to define downwardly extendinghooklike projections, and means comprising a metal collar having aflange extending upwardly into said notches of said legs and clampinglyengaging said hook-like projections to resist movement of any kind ofsaid legs relative to said column when said locking means is securedthereto.

2. The chair base according to claim 1 in which said metal collar hasholes therethrough and screws extend through said holes into threadedholes in said column to connect said collar to the lower end of saidcolumn.

3. The chair base according to claim 2 in which said locking collar issubstantially flush with the lower edges of said legs.

4. The chair base according to claim 1 in which the u per portions ofsaid inner ends of said legs have undercut notches therein and the upperends of said recesses in said column are complementary to said notchesand engage the same clampingly when said locking collar is connectedoperatively to said column.

5. The chair base according to claim 1 in which said column is tubularto provide a central bore to receive longitudinally a supporting shaftdepending from a chair seat and said vertical recesses in the lower endsthereof comprise slots extending entirely through the walls of saidcolumn, thereby to facilitate the formation of said recesses such as bya milling cutter.

6. The chair base according to claim 5 in which the lower end of saidcolumn is shaped to accommodate the upper surface of the locking collarand the interengagement of the upwardly extending flange of said collarwith the hook-like projections on said legs comprise the sole meanspreventing upward movement of the outer ends of said legs relative tosaid column.

7. The chair base set forth in claim 5 further characterized by theinner ends of said legs having notches in the upper portions thereofdefined by angularly related surfaces adjoining each other andrespectively abutting the exterior vertical surface of the column andthe inner ends of the slots in said column to prevent inward and upwardmovement of the upper portions of said legs relative to said column,whereby said legs are retained in fixed radial position relative to saidcolumn.

8. The chair base set forth in claim 5 in which said locking means alsoincludes a sleeve surrounding said column and movable downward thereonfrom above said legs to engage the upper portions thereof and operableto force the lower notches thereon into firm engagement with said flangeof said collar.

9. The chair base set forth in claim 8 further char-acterized by saidsleeve having slots extending upward from the lower end thereof andcomplementary to the slots in said column and similarly receiving theinner ends of said legs, the upper ends of the slots in said sleevebearing against the upper surfaces of said legs.

10. The chair base set forth in claim 8 further including threaded meanson the upper portion of said column engaging the upper end of saidsleeve adjustably to secure said sleeve in operative position relativeto the inner ends of said legs. 1

References Cited in the file of this patent UNITED STATES PATENTS1,052,799 Collinsworth Feb. 11, 1913 1,421,398 Burchess July 4, 19223,078,063 Frankl Feb. 19, 1963

1. A CHAIR BASE COMPRISING A CENTRAL SUBSTANTIALLY VERTICAL COLUMNHAVING A PLURALITY OF RADIAL OPEN-ENDED RECESSES EXTENDING VERTICALLYUPWARD FROM THE LOWER END THEREOF, AND A PLURALITY OF CANTILEVERMETALLIC LEGS EXTENDING RADIALLY OUTWARD SPIDER-LIKE FROM THE LOWER ENDOF SAID COLUMN IN CIRCUMFERENTIALLY SPACED RELATIONSHIP TO EACH OTHERAND THE INNER ENDS OF SAID LEGS BEING CLOSELY COMPLEMENTARY TO ANDRECEIVED WITHIN SAID RECESSES, IN COMBINATION WITH MEANS DETACHABLYCONNECTING SAID INNER ENDS OF EACH LEG WITHIN SAID RECESSES OF SAIDCOLUMN COMPRISING LOCKING MEANS DETACHABLY CONNECTED TO THE LOWER END OFSAID COLUMN, THE INNER ENDS OF SAID LEGS HAVING NOTCHES EXTENDINGUPWARDLY FROM THE LOWER